Disconnect switch



April-16, 1957 Filed Oct. 20, 1952 4 Sheets-Sheet 1 INVENTOR$ Haw/14wd-e/wi/z Jen/0e #1517 BY April 16, 1957 H. w. GRAYBlLL ET AL 9DISCONNECT swz'rcn Filed Oct. 20, 1952 4 Sheets-Sheet 2 April 16, 1957Filed Oct. 20, 1952 GRAYBILL ET AL DISCONNECT SWITCH 4 Shets-Sheet a INV EN TOR5 #04024; M- fiewyiru.

lmwe Allin? April 16, 1957 H. w. GRAYBILL ETAL DISCONNECT SWITCH 4Sheets-Sheet 4 Filed Oct. 20, 1952 Irma/rm United States ?atent (l2,789,189 DISCONNEQT SWITCH Howard W. Graybill and Arthur M. Zeth,Greenshnrg, Pa., assignors, by mesne assignments, to I-T-E CircuitBreaker Company, Philadelphia, Pa, a corporation of PennsylvaniaApplication Gctoher 20, 1952, Seria 315,629 8 Claims. (Cl. 200176) Ourinvention relates to disconnect switches and is more particularlyrelated to a novel switch for a uniform and consistent high pressurespot contact which has advantages over the prior art switch whensubjected to a short circuit condition.

Our invention relates to disconnecting switches of the high voltagehook-stick operated type. These switches have one or more contactblades, usually rectangular in cross section, which have one endattached to a hinge terminal and which rotate about the hinge terminalinto and out of engagement with a second terminal or break jaw to closeand open the switch. This operation is usually accomplished from aremote point by means of an insulated switch stick which engages a pullring at the break end of the blade.

The prior art disconnect switches have a Single or plurality of highpressure spot or line contacts in preference to surface to surfacecontact. That is spot or line contact of high pressure and limited area,permits metal to metal contact through dust, oxide, and sulphide filmsand ice.

However, heretofore, in order to obtain high pressure spot contacts theswitch blades to be used in the disconnect switches were subjected to acoining operation at the break jaw end of the contact blades. That isthe blade was coined on diametrically opposite sides in order to obtainprotrusions which would act as contact buttons for the switch blade.extra metal which would form a portion of the contact button, it wasnecessary to reduce the cross sectional area of the blade immediatelyadjacent to the contact button. This type of switch blade had severaldisadvantages. For example, during short circuit conditions the heatgenerating thereby at the contact spots had to pass through theconstricted area which resulted from the coining operation. Theconstrictions not only increased the heat generated but also limited theheat flow and thereby resulted in increased temperature rise of thecoined con-, tact spot.

Furthermore, the fact that the coined contacts were in diametricallyopposite sides of the blade arm resulted in extreme concentration of theheat generated thereby causing possible damage to the blades.

Accordingly, the net result is a marked limitation of the short circuitcurrent the disconnect switch will carry without damage thereto.

It is also noted that the disconnect switches of the prior art useannealed copper stationary contact fingers which are backed up byphosphorous bronze springs in order to achieve resilient means to obtainhigh contact pressure. However, this system results in a switch havingindeterminate contact pressure which could not be calculated due to thefact that stresses in the copper fingers are unknown. Furthermore, thecopper fingers are subjected to cold flow so that the contact pressuredoes not remain constant and even when the switch is first assembled itis possible to have a wide variation in the contact pressure dependingon how the pressure is adjusted.

However, in order to obtain the.

In the novel disconnect switch of our invention, we

propose to obtain high pressure spot contact by providing the blademember with two or more raised contacts of spherical radius on one sideto touch the break tongue and one or more raised contacts of sphericalradius on the other side to touch the contact spring member wherein icethe raised contacts are spaced apart along the axis of the blade. Theraised contacts are created by a forming operation rather than a coiningoperation and hence are created without the necessity of reducing thecross sectional area of the blade.

Thus with this novel construction for the switch blade the short circuitcapacity of the disconnect switch will be materially increased due tothe fact:

1. That the contact spots on either side of the blade are spaced fromeach other:

2. That the contact surfaces are raised contacts of spherical radiuswith no constrictions on reduced cross sectional area.

Hence with the above mentioned changes, the heat generated will be:

1. materially reduced due to the increased cross sectional areaavailable and 2. more readily dissipated due to the fact that the raisedcontacts are spaced from each other.

Our novel disconnect switch also difiers from the switch of the priorart by providing stationary spring contact members of a precipitationhardened alloy which are cantilevered from the base of the switch toreplace the annealed copper fingers backed up by phosphorous bronzesprings used in the prior art arrangement. Our invention also includesprecision spacers positioned between the break tongue and the abovementioned spring contact members to insure a controlled distance betweenthese two units, to enable the blade members to impart a predeterminedcantilever stress on the spring contact members to supply proper contactpressure.

A novel latching device, to maintain the switch in closed positionduring the occurrence of a short circuit, used in connection with ournovel disconnect switch, is described and claimed in co-pendingapplication Ser. No. 315,619, filed October 20, 1952.

Accordingly, it is a primary object of our invention to provide a highpressure spot contact disconnect switch of maximum short circuitcapacity which is consistent with practical and economical designpractice.

It is a further object of our invention to provide a novel disconnectingswitch which is relatively inexpensive to construct and eliminatesunnecessary brazing and milling operations.

It is a further object of our invention to provide a disconnect switchin which the contact pressure can be readily calculated and held withinclose limits by simple test during assembly operations.

Another object of our invention is to provide a switch construction inwhich the contact pressure is independent of the switch assembled andwhich can be readily inspected to determine contact pressure.

Still another object of our invention is to provide a disconnect switchin which stationary contact springs which carry a portion of thecurrent, are made from high strength, high conductivity precipitationhardened alloy (such as beryllium copper) which are not subject toannealing at temperatures encountered in this type of switch.

Still a further object of our invention is to provide a simple switchconstruction in which contact pressure can be readily determined bychecking the thickness in the contact spring spacers.

Still a further object of our invention is to provide a novel switchblade in which the contact points are spaced apart so that heatgenerated under short circuit conditions will be distributed over agreater area.

Still another object of our invention is to provide a novel switch bladefor a disconnect switch wherein there are no constrictions in the bladeto restrict the flow of heat.

A still further object of our invention is to provide cantilevered typespring contact members which are arranged to carry a portion ofthe-switch current as well as to supply contact pressure.

A still further object of my invention is to provide a novel switchblade for a disconnect switch in which the raised contacts therein arecreated by a forming operation rather than a coining operation.

These and other objects. of our invention will be ap.- parent from thefollowing description in which:

Figure l is a side view of our novel disconnecting switch mounted on aframe and showing same in closed position with heavy-line, and in openposition with dotted lines.

Figure 1a 'is an enlarged side view of the disconnect switch showing thehinge terminal, blade assembly and jaw terminal. a

Figure '2 is a top view of Figure 1.

Figure 3 is a view taken along the line 3'-3 of Figure laand-shows theengagement ofthe spherical radius contacts of the switch blade with thebreak tongue and the cantilevered stress on the-spring contacts. 7

Figure 4 is a view taken along the line'kd of Fig ure' la and-shows theengagement of the switch blades with the bladelatch.

Figure 5 is a top view of the switch blades used in ourswitch andillustrates the novel spherical radius contacts which are formedtherein, the indentations ofblade for latching engagement with the shortcircuitlatch, and the-inwardly protruding cam surfaces.

Figure 6 is a side view of the switch-blade of'Figure 5.

Figure 7 is a view taken along the line 77 of Figure 6 showing thedetails of the spherical radius contactsand the cammed surface forseparation ofthe blades by means of the pull ring.

' Figure 8 is a view taken "along the line 3' 8 of Figure 5 showing aside view of the camm'ed surfaces of the switch blade. 7

Figure 9 is-a view taken along the lines 99 of Figure 5' showing theindented upper portion of the switch blade for engagementwith the shortcircuiting latch,

Figure It) is a perspective view showing the jaw end of our noveldisconnecting switch.

'Referring to Figure 1, the insulator units '10 and 11 are mounted onthe base 12 by means of bolts 13. The upper ends of the insulator units16 and 11 support the terminal contacts 14 and 15 which are attachedthereto by means of bolts 17 and 13. The terminal connector 14 isprovided with a horizontal extension 16 in which openings 17 and 18 areprovided to permit connectionof the electrical'lir ie thereto.

'A verticahextension E of the terminal connector 14.

has -the hinge ends of the blades 30 and 31 rotatably n s the eqn by mans to. pin 2-. e r inal onnector is ate t th j w nd. o e conn ng switchis provided with ahorizorital extension 33. and

34in which openingsSS and 26 are provided for proper connection to theline. i

As'best'seen in Figure 1, 1a, 3 and 10, the terminal connector 15 has avertical extension 40 which forms the-break tongue of our noveldisconnecting switch. Thev entire terminal connector 15, comprising thehorizontal extensions 33 and 34 and the vertical extension 49 may becopper casting with the vertical sides of the break tongue ddmachined toobtain parallel finished surfaces.

It is necessary to machine the sides 40a and 40b of the break tongue 40:

1. So that they are parallel and have smooth surface for properelectrical engages with the spherical radius contacts.

'2. To provide a flat surface for the accurately chined spacers 44' and45 so that the resilient spring contacts41wand 42 can be properly spacedfrom the parallel sides.

By' this means, an accurately predetermined consistent contact pressurecan be obtained.

Sprlng :contact'arms 41 and 4.1 as best seen in Fig-..

strength, high conductivity precipitation hardened alloy such asberyllium copper which is not subject to annealing at temperaturesencountered in the operation of-the disconnecting switch. As seen in thefigures, thespring contacts 41 and 42 are cantilever mounted so that thecontact blade will place a cantilever stress on themwhen it is closedover and touches the parallel sides of the break tongue 40.

The spacer units 44 and 45 are machined members which accuratelyposition thespring contacts 41 and 42 to control the distance betweenthem and the sides'40u and 49b of the break tongue 40 are machinedfinished to insure that these units are smooth-and parallel't'o eachother.

As best'seen in Figures 3 and 10 the spring'contact members 41 and 42are mounted by means of the bolt and nut 46-47 at their lower end sothat the engagement of the knife blades 3! and 31 with the break tongue48; as indicated, will cause a cantilevered stress to be placed on thespring contact arms. By this arrangement, highuniform consistent andpredetermined'contact pressure is insured.

As seen in Figure la, 4 and 10, the break tongue 40 has a step extension46; a short circuiting latch 50, comprising U-shaped legs 51 and 52which straddle the step extension 49; and is attached thereto by meansof connecting member 53. e short circuiting latch 50'has an'up wardextending step section 55' which serves as 'a step'or foundation for thepry out extension 81 of the pull ring as will hereinafter be more fullyexplained.

The short circuiting latch member 59 is also provided with a secondupwardly extending portion 57 which has a latching portion 58 with astep section 59 and 6!). The;

1. Raised'contacts 7s, 74, 7s, 7s, 77, '78 of spherical radius on a.Be-75 and 76--78 on one side to engage break ns l-e40 I2. 74 and 77 onthe other side to engage spring contacts '41 and v42. 7

Z. Inwardly protruding portion 94 and 95 to torrnn canimdsurface bywhich the blades can be separated to'enable their removal from latchengagement with a short circuited latch 53.

3., Indented upper section and 91 at the jaw end inorder to. enable theblades to belatched by the short circuited latch member 58.

As best seen in Figures 5 and 7, the contacting sur faces 73 through 78for the switch blade are formed by providing a plurality-oi sphericalradius protrusions havingapproximately a /3" radius. This sphericalradius contacts are made by a forming operation on the switch blades.30'and 31; so that no reduced cross-section or constrictions result fromtheir formation. Thus as seen in Figures-5 and 7, the switch blade fiflis providedwith raised .contacts73 and 74 and 75. The, raised contacts73.,and 75. protrude approximately 1 on one side of. the. blade and; theraised'contact 74 protrudes-the same distance from theopposite side ofthe switch blade. In

like manner the switch blade 31 is formed with raised contacts 76 77 and78. Thus as seen-in. Figure 6,-the.

plurality of spherical radius contacts 73, 74 and 75 may be positionedin alignment with the long axis of the switch blade 30. Figure 3, whichis a view taken along the line 33 of Figure la, and Figure 10illustrates the manner in which the inwardly protruding spherical radiuscontacts 74 and 75 engage the break tongue 40 and the manner in whichthe outwardly protruding spherical radius contacts 74 and 77 engage thevertical extending spring contacts 41 and 42 respectively.

It will therefore be apparent that the engaging area of the inwardlyprotruding spherical radius contacts 73-75 and 76-78 are axially spacedfrom the outwardly protruding spherical radius contacts 74 and 77 tothereby increase the area of the switch blade which will be exposed tothe low excess heating in the event of a short circuit condition.Furthermore, these contact surfaces are provided from the originalmaterial of the switch blades 30 and 31 without the necessity ofreducing its cross-sectional area and thereby prevents any possibilty ofheating due to any constriction of the conducting material.

As above noted, the switch blades 30 and 31 are pro vided with aninwardly extending cammed means 90 and 91 as seen in Figures 5, 7, 8 and10. These inwardly extending cammed sections 90 and 91 are positioned tothe left of the switch blade connecting studs 92 and 93 as seen inFigures 2 and 6. As will hereinafter be apparent, the cammed means 90and 91 are provided to enable the pry out blade 81 of the pull ring 80to wedge therebetween in order to cause a separation of the switch blade30 and 31 to enable release from the short circuited latch 58.

As above noted, the switch blades 30 and 31 are also provided withinwardly extending indentations 94 and 95 positioned at the upper endthereof near the jaw end of the blade. As best seen in Figure 9 and 10the indentations 94 and 95 protrude inwardly approximately and as seenin Figure 5 are positioned on the switch blade 30 and 31 between thespherical radius contacts 7578 and cammed surfaces 90 and 91. Theindentations 94 and 95 are provided to enable latch engagement betweenthe switch blade 30 and 31 and the latch means 58 as will hereinafter bemore apparent.

Referring now to Figures 1, la, 2, 3 and 4 and'lO, the disconnect switchis shown in the closed position. In this position the inwardly extendingindentations 94 and 95 at the upper end of the switch blade arepositioned under the latching surfaces 59 and 60 of the latch means 58.In this position the lower ends 101 and 102 of the switch blade 30 and31 are seated on the horizontal ledges 103 and 104 at the lower end ofthe latch unit 55. Thus it will be apparent that the blades 30 and 31 ofthe disconnect switch are sandwiched between the latching surfaces 59and 60 of the latch head 58 and the horizontal ledges 103 and 104 of thelatch means 55 to prevent vertical movement thereof. On the occurrenceof a short circuit condition, the loop circuit created at the contactpoints will create an electromagnetic force to blow the switch bladesupwardly. However, due to the latch engagement between the indentations94 and 95 of the switch blades 30 and 31 with the latch surafces 59 and60 of the latch unit 58, the disconnect switch blades 30 and 31 willremain in closed or latched position.

The manner in which the switch blades 30 and 31 are moved from theclosed position of Figure l and la to the open position (indicated bythe dotted lines in Figure 1) will now be described. The pull ring 80 ispivoted on the pin 92 between the switch blades 30 and 31 and isprovided with a pry out extension 81 positioned between the connectingpins 92 and 93. When the operator desires to open the switch, an upwardcontinuous pulling force is supplied to the pull ring 80 by means of ahook stick of any other desirable means. This causes counter-clockwiserotation of the pull ring 80 about its point 98 resulting in: 1

d 1. The wedging of the pry out fingers 81 between the cammed surfacesand 91 of the switch blade 30 and 31 respectively. Due to the resiliencyof the blades 30 and 31, they will be separated due to the abovementioned wedging action resulting in the removal of the bladeindentations 94 and from the latch surfaces 59 and 60 of latch 58.

2. The pry out finger 81 will engage the surface of the latch means 55and thereby be prevented from further downward movement thereof.

As best seen in Figure 1, the pull ring is constructed withapproximately a two to one mechanical advantage. Thus as the pry outfinger 81 engages the horizontal switch 110 of the latch means 55 thepulling force on the pull ring 80 which previously resulted in mererotation of the ring about the pivot 98, will now result in bothrotation and upward movement of the pull ring 80 due to the seating ofthe pry out finger 81 on the horizontal flat base 110. Hence by a singlecontinuous motion the switch blade 30 and 31 can be moved from theclosed position of Figures 1 and 1a to the open position indicated bythe dotted lines. Accordingly, with this novel latch and pry outmechanism, the switch blade is positively located in the closedposition, and the disconnect switch may be moved to full open positionwith a single continuous motion of only one moving part other than blademembers themselves.

Pin means 92 and 93 are positioned through the contact blades 30 and 31to limit the movement of the pull ring 80.

Accordingly, in summary, we have provided. a novel disconnect switch toobtain high pressure point contact by providing blade members withraised contacts of spherical radius on one side to touch the breaktongue and one or more raised contacts of spherical radius on the otherside to touch the spring contact member where in the raised contacts arespaced apart along the axis of the blade. The raised contacts arecreated by a forming operation rather than a coining or dying operationand hence are created without the necessity of reducing thecross-sectional area of the blade. Thus with this novel construction forthe switch blade the short circuit capacity of the disconnect switchwill be materially increased due to the fact:

1. that the conducting surfaces on either side of the blade are spacedfrom each other.

2. that the contact surfaces are raised contacts of spherical radiuswith no constriction on reduced crosssectional area.

Hence with the above mentioned changes, the heat generated will be:

1. materially reduced due to the increased cross-sectional areaavailable and raised contacts are spaced from each other.

Our novel disconnect switch provides stationary spring contact membersof a precipitation hardened alloy which are cantilever from the base ofthe switch to replace the annealed copper fingers backed up byphosphorous bronze springs used in the prior art arrangement. Ourinvention also includes precision spacers positioned between the breaktongue and the above mentioned spring contact members to insure acontrolled distance between these two units, to enable blade members toimpart a predetermined cantilever stress on the spring contact membersto supply proper contact pressure.

In the foregoing, we have described our invention only in connectionwith preferred embodiments thereof.

Many variations and modifications of the principles of our inventionwithin the scope of the drawings are herein obvious. Accordingly, weprefer to be bound not by the specific disclosure herein, but only bythe append ing claims.

We claim: 1. In disconnect switches comprising a switch blade,

a breaktonguei spacer means and'a spring contacn'naid closed over andtouching said parallel side of-said break tongue-causing a cantileveredstress on said spring contact to supply contact pressure, said spacermeans con nected between said spring contact'and a parallel side of saidbreak tongue'to accurately. govern the distance therebetwcen, saidspacer-means providing an accurate predetermined distance between saidparallel side of said break-tongue andwsaid spring contact to'insure apredetermined contact pressure from said cantilevered stress onsaidspring contact,

2. In a disconnecting switch having an open and closedpositionucomprising a break tongue,aswitch blade and a spring contact,said break tongue being a single relativelyheavy member finished sothatthe two sides thereofi are parallel, said switch blade rotatablymounted to close over and touch a parallel side of said break tongue;said spring contact being made of a high-strength highconductivity alloyand mounted on said disconnecting switch at one end thereof, said springcontact positioned to-supply contact pressure between said switch bladeand said break tongue, said switch blade being formed with a pluralityof raised contacts ofzspherical radius, at. least one raised contact onone side of said switch blade to engage said fiat side of said tongueand at leastone raised contact on the opposite side of said. switchbladeto engage'said contact; said plurality of .raisedcontacts permittinghigh: pressure spot contact between said switch blade, said tongue andsaid contact; said raised contacts being:formed on said. switch bladewithout reducing the a cross-sectional area of said switch blade tothereby preventaoverheating at any constriction therein, said raisedcontacts on opposite sides of said switch blade being spaced along theaxis of said switch blade to further insure that heating of thecontacting surfaces due to fault current will occur at widely separatedpoints.

3. In adisconnecting switch having an open and closed positioncomprising a break tongue, a switch blade and a spring contact; saidbreak tongue being a single relatively heavy member machined so that onesurface thereof is flat, said switch blade rotatably mounted to closeover and touch said flat side of said break tongue; said spring contactbeing made of a highsstrength high-con ductivity alloy, said spacermeans positioned between said flat side of said. break tongue and saidspring contact, 7

said spring contact being secured to said spacer means andsaid breaktongue, said spacer means accurately controlling the distance betweensaid fiat side of said break tongue andsaid'spring contact; said springcontact supplying contact pressure between said switch blade and said'break tongue, said .spacer means controlling the magnitude of saidcontact pressure.

4. In adisconnecting switch having an open and closed positioncomprising a break tongue, switch blades and stationary contacts; saidbreak tongue being a single relatively heavy member finished so that thetwo sides thereof are parallel, said switch blades rotatably mounted toclose over and touch said parallel'sides of said break tongue; saidstationary contacts being made of a resilient position, comprising afirst and second switch blade-with at hingedendand a jawend,saidtswitch.blades-rotatablY mounted at saidhingezendand-positionedfor contact engagement and disengagement at saidjaw end; a break tongue,a -pair of springcontacts, and spacermeans located. at said jawend,-said break tongue havingparallel sides and positioned to havesaid-pairof blade-members close over and touch said parallel sides oisaid break tongue when. said disconnecting-switch is in said closedposition, said spring contacts being mounted on said spacer meansandrpositionedparallel to said parallel sides of said break tongue,.said spring-contacts arranged to urge said switch blades against saidparallel surfacesof said break tongue at apredeterrninedpressure, saidspring contacts .postioned from said parallel surfaces by said spacermeans.

6. In a disconnecting switch having'an open and closed position,comprisinga. first and second. switch blade with a hinged end and a. jawvend, said switch blades'rotatably mounted at said hinged-.endandpositioned for contact engagement sin-disengagement at said-jaw end; atongue, a pair of spring contacts, and spacer means located at said jawend, said tongue having parallel sides and po-- sides of Said-tongueandat least one raised contact on the opposite -side-of saidswitch bladesto engage said spring contacts; said plurality of raised contactspermitting high pressure .spotcontact between said switch blades, saidtongue and said spring contacts.

7..In disconnect switches comprising switch blades, a tongue, spacermeans and spring contacts; said tongue being 'a single relatively heavy.member with parallel sides, said switch blades connected to close overand touch the parallel sides of said tongue, said spring contactspositioned parallel to said parallel sides of said tongue, saidswitchblade members when closed over and touching said parallel sides ofsaid tongue causing cantilevered stress on. said spring contacts tosupply contact pressure, said spacer means connected between saidspring. contacts. and said'parallel sides of said tongue toaccuratelygovern thedistance therebetwcen, said spacers providing anaccurate predetermined distance between said parallel sides of saidtongue and. said spring. contacts to insure a predetermined contactpressure from said cantilevered stress on said. spring contacts.

8. In disconnect switches comprising switch blades, a tongue, spacermeans andcontacts; said tongue being a single relatively heavy memberwith parallel sides, said switch blades connected to close over andtouch the parallel sides of said tongue, said contacts being made of aresilient material andpositioned parallel to said parallel sides of saidtongue, said switch blade members when closed over and touching saidparallel sides of said tongue causing a cantilevered stress on saidcontacts to supply contact pressure; said spacer means positioned tocontrol the distance between said parallel sides of said tongue and saidcontacts to insure thatsaid cantilevered stress supplies apredeterminedcontact pressure.

ReferencesCited inithe. file of this patent UNITED STATES PATENTS1,898,135 Massey- Feb. 21, 19.33 1,935,516 -M'u'sgrave .Nov. 14, 19332,157,174 Hoyej May 9, 1939 2,521,826 Caldwell et a1. Sept. 12,1950

